WO1980001634A1

WO1980001634A1 - Subscriber card for videotex receiver and loading set for this card

Info

Publication number: WO1980001634A1
Application number: PCT/FR1980/000017
Authority: WO
Inventors: L Guillou
Original assignee: France Etat; Telediffusion Fse; Secretaire Detat Postes & Tele
Priority date: 1979-02-06
Filing date: 1980-02-05
Publication date: 1980-08-07
Also published as: ES488281A0; EP0014654B1; ES8106995A1; CA1156753A; JPH027233B2; FR2448826A1; EP0014654A1; US4352011A; FR2448826B1; JPS56500074A; DE3069688D1

Abstract

This card is characterized in that it comprises a programmable memory comprising a plurality of locations to receive subscription digital block (Ci), a read-only-memory containing instructions, a computer circuit receiving, from the receiver where the card is introduced, digital messages (Mi) and receiving from said programmable memory a subscription digital block (Ci), said circuit being capable to develop a parameter algorithm by subscription keys (Ci) upon instructions from the second read-only-memory and providing after calculation a digital signal representative of a service key (K). Application to videotex systems, particularly of the ANTIOPE type.

Description

SUBSCRIPTION CARD FOR VIDEOTEX RECEIVER AND CHARGING STATION FOR SAID CARD

The subject of the present invention is a subscription card for a videotex receiver and a station for loading said card.

It finds application in the transmission and display of information on television receivers for any purpose of entertainment, information or teaching. The invention essentially applies to the so-called "ANTIOPE" system (Digital Acquisition and Televisualization of Images Organized in Writing Pages), and to the so-called "TITAN" system (Interactive Teletext Terminal and Dialing Call). We know that it is essentially, for the first, a system of diffused videotex (therefore unidirectional) allowing to insert on television channels alphanumeric information organized in pages and magazines, and, for the second, an interactive videotex system (therefore bidirectional) compatible with the ANTIOPE system and allowing access to databases (general information, directories, etc.) and to interactive services (transactions, messages, teaching) by the telephone network. In the ANTIOPE system, information is disseminated by a procedure called "DIDON" (Digital Data Diffusion) which is a packet diffusion procedure, compatible with the broadcasting of the television signal.

Many articles or patent applications have already described these systems, in particular the ANTIOPE system, a detailed description of which can be found in the following documents which must be considered as incorporated in the present application:

- the article by Y. GUINET entitled "Comparative study of teletext systems in broadcasting. Some advantages management of the distribution of packet data applied to teletext "published in the EBU journal Cahier Technique, nº 165, October 1977, pages 242 to 253;

- the article by B. MARTI and M. MAUDUIT entitled "ANTIOPE", teletext service published in the review "Radiodiffusion Télévision", 9th year, Nº 40, November-December 1975, 5/5, pages 1B to 23;

- the "Specification of the teletext system" ANTIOPE ", published by the Joint Center for Television and Telecommunication Studies (CCETT);

- French patent application no. 75 18319, filed on June 6, 1975 and entitled "Data dissemination system";

- French patent application no. 16 27212, filed on September 6, 1976 and entitled "System for digital transmission and display of text on a television screen";

- French patent application No. 76 29034, filed on September 22, 1976 and entitled "Improvement to digital transmission systems and display of texts on a television screen"; - the request for French addition certificate nº 77 17625, filed on June 3, 1977 and entitled "Data dissemination system".

The advent of ANTIOPE or TITAN type services raises the question of the taxation of these services, that is to say the implementation of a system allowing the identification and control of audiences. This question also arises more generally for any service that tends to make the broadcasting networks profitable by making better use of resources. Subscription-type taxation constitutes a flexible and lasting relationship between a service and its users. It is in diffusion especially that such a method of taxation finds its justification.

Consumption-type taxation can also be used; this method of charging is fundamental for "interactive" systems (in which a dialogue is established between the subscriber and the information source, as is the case for TITAN); but it remains secondary in broadcast systems (in which information is transmitted unidirectionally to subscribers, as is the case for ANTIOPE).

Intermediate systems, known as "quasi-interactive" may arise, in which the content of the broadcasting source is constantly modified to meet the requests of users which are transmitted by a public data network. The advent of new very large capacity means of broadcasting (satellites) will greatly develop this quasi-interactive mode, making it necessary to implement a system to control access to the information offered.

This problem of access control poses above all that of locking information on transmission and unlocking on reception. This problem must naturally be resolved taking into account the specificity of the teletext system to be checked. In particular, the method of scrambling information and that of recovering the intelligibility of information must not penalize the performance of the system.

The French patent application nº EN 79 02994 filed on February 6, 1979 and entitled "Videotexmuni system of means of control of access to information" rightly describes an electronic lock capable of locking information on transmission and a key to unlock it at reception. Without going into the details of this system, its essential elements can be briefly described in order to better understand the present invention. This system is shown in FIG. 1. This system firstly comprises known elements characteristic of the ANTIOPE videotex system, namely a transmission center 2 and receiver stations 4.

The emission center receives information from one or more sources 5 and it includes: - a means 6 for composing a magazine made up of pages organized in rows of characters, if this means is not already in the information source;

a circuit 10 for storing the magazine in the form of digital signals grouped into bytes (8 binary elements), a junction 11 connected to circuit 10,

- A broadcast multiplexer 12 for inserting information into the lines of a television signal, this means implementing the DIDON procedure mentioned above. Each receiving station includes:

a circuit 14 for receiving and demodulating said television signal,

a channel 16 for processing the video image signals,

a channel 18 for processing digital signals, this channel comprising in particular a digital data decoder, and finally,

- A display member 20.

In this type of system, the digital signals transmitted are grouped in the form of bytes, which are divided into control bytes and data bytes. The command bytes indicate in particular headers and end of pages as well as headers and end of rows. The data bytes, inserted between command bytes, correspond to characters contained in the rows. All these bytes, whether control or data, include a most significant binary element which is an element of evenness. The bytes whose 6th and 7th binary elements are zero are control bytes and they play a particular role in the system which is the subject of the request cited above.

The system described in this request also comprises: A) - in the transmission center 2:

a) a generator 22 delivering a humic signal representing a service key K, this key changing randomly at determined intervals which are for example of the order of a few minutes; b) a locking automaton 24 comprising: i) a comparator 28 to an input connected to the circuit 10 for memorizing Ion of the magazine from which it receives clear bytes; this comparator is capable of distinguishing, among these clear bytes, those whose 7th and 6th binary elements are zero; this comparator has two outputs 31 and 32, the first conveying these bytes with 7th and 6th null bits and which is connected to the broadcast multiplexer 12 (through a junction 11 '), and the second conveying the clear bytes dj of which 7th and 6th binary elements are not null; ii) a logic circuit 34 of the OU-exclusive type with two inputs, one connected to the second output 32 of the comparator 28 from where it receives the clear bytes dj at 6th and 7th non-zero binary elements; this logic circuit has an output which conveys odd encrypted bytes Dj, the encrypted bytes then being directed (through the junction 11 ') to the broadcast multiplexer 12; c) a generator 26 of encrypting bytes Cj, controlled by the automaton 24 from which it receives bytes indicated the page numbers and row numbers of the data to be transmitted and the signal corresponding to the service key K; this byte generator 26 delivers, for each byte of data dj of a viewable row, a byte encrypting Cj, this byte having an 8th binary element of parity and of the 7th and 6 th zero binary elements, this byte being applied to the second input of gate 34.

B) - in each receiving station 4:

d) a circuit 36 delivering a digital signal representing the service key K in progress in the transmitting station,

- e) an unlocking machine 38 comprising: i) a comparator 42 to an input receiving the encrypted bytes; this comparator is able to distinguish, among these encrypted bytes, those whose 7th and 6th binary elements are zero, this comparator having two outputs 43 and 44, the first conveying these bytes whose 7th and 6th binary elements are zero, this first output being connected to the display member 20, the second conveying the encrypted bytes Dj whose 7th and / or 6.pme binary elements are not zero, ii) a logic circuit 46 of the DU-ex-siusive type with two inputs, one connected to the output 44 of the comparator from which it receives the encrypted bytes Dj, this logic circuit having an output which carries decrypted bytes dj which are then directed towards the display member 20.

f) a generator of decrypting bytes, controlled by the unlocking automaton from which it receives the bytes indicating the page numbers, the numbers in the rows of the transmitted data, and the signal corresponding to the the current service key K; this deciphering byte generator has an output 41 which delivers, for each encrypted byte received, a deciphering byte Cj having a most significant binary element which is forced to zero and 7th and 6th zero binary elements, these bytes being applied to the second entrance to door 46. Such locking and unlocking means make it possible to advantageously resolve the problem of taxation mentioned above. To this end, the invention obj and the cited application proposes to use, in addition to the service key, whose role has just been defined, subscription keys which are generated randomly by a data center. tax management. These keys have a relatively long lifespan (from 1 to 12 months), compared to that of the service key equi is of the order of a few minutes).

To illustrate the operation of this dual key system, we can take an example of a subscription scheme which would use four types of subscriptions: 1 month, 3 months, 6 months and a year. In addition to its duration, a subscription is characterized by its start month. With such a scheme, during a given month and for a given service, there are therefore 22 subscription keys likely to be used by users; a monthly key, three quarterly keys, six semi-annual keys and twelve annual keys:

Each month, the tax management center provides each distribution center with a list of 22 current subscription keys for each service distributed by this center. In addition, it provides subscription sales outlets with another list of 4 keys that will start the following month (one month, three months, six months and one year), for each service, with the subscription prices. A suitable machine, installed in each point of sale, register some of these keys in the form of blocks of subscriptions on supports provided for this purpose (eg smart cards of the "credit card" type) These cards are then introduced by users of the service into their posts receiver.

For each paying service, approximately every five minutes, a new key to service K is generated at random by each broadcasting center concerned. Thus, during a session of a service (an hour or a few hours), a few dozen keys of the service can succeed one another.

As soon as a broadcasting center generates a new service key K, it calculates, for each subscription key in progress C _i for this service, a message M _i by an algorithm configured with the keys C _i playing the role of parameters.

Thus, for a service with the subscription scheme indicated above, at all times ,. 22 different messages are in effect. The lifetime of a message is equal to that of the service key K, and for a given service, at any time, there are as many messages as there are subscription keys in progress.

The set of messages M. in force constitutes, the access control information associated with the service broadcast. This access control information is obviously not locked by the electronic lock.

This particular system of subscription charges involving two keys, one subscription, the other service, is the subject, in its essential elements, of French patent application No. 79 02995 filed on February 6, 1979 and entitled "Information transmission system provided with access control means".

These information access control means are represented in FIG. 1. They comprise: A) - a subscription management center 100, which generates digital signals corresponding to the subscription keys C _i , these keys changing randomly at long intervals of the order of a month and according to diagrams similar to that which has been indicated above by way of example;

B) - in the emission center;

a circuit 102 for forming messages M _i which receives from circuit 100 the signals corresponding to said subscription keys C _i and from generator 22 the signal corresponding to the service key K.

These messages are obtained using an algorithm parameterized by C _i . Circuit 102 delivered

re as many messages M _{i as} there are subscription keys C _i , these messages changing with the service key K. All of these messages are organized in a special page 104 called the access control page. This page is transmitted cyclically by the multiplexer 12, but cannot be viewed; C) - in each receiving station: i) a subscription medium 106 which contains a memory 108 in which is registered at least one subscription block representing one of the subscription keys C _i ; j) a circuit 110 for restoring the service key K, connected, on the one hand, to circuit 18 from which it receives a message M _i extracted from the access control page and selected using the index d subscription and, on the other hand, to the memory 108 of the subscription medium from which it receives the subscription key C _i . This circuit 110 develops an alςorithm which allows to

restore the signal corresponding to the service key K used in the transmitting station; D) - at least one loading station 112 connected to the subscription management center 100 from which it receives the signals corresponding to the different subscription keys C _i generated by this center; each of these stations is capable of temporarily receiving subscription media and of writing one of the subscription keys C _i into their memory 108.

The subject of the present invention is precisely a particular embodiment of a subscription medium such as the assembly 36 of FIG. 1 and a loading station such as the station 112 of this same figure.

The card of the invention is of the type of credit cards used in the field of commerce and banking and, as such, it includes known elements such as support, interface, information processing circuits, etc. But it contains complementary means which make it capable of fulfilling a new function in a system for controlling access to information as just described. This function is essentially to allow the opening of the electronic lock at the videotex receiving stations.

More specifically, the present invention relates to a subscription card for videotex receivers, this card comprising: a) a support, b) information processing means comprising in particular a control unit managing an arithmetic and logical unit and a random access memory, c) an interface allowing exchanges between the card and the device into which it is inserted (charging station or receiver), characterized in that it further comprises: d) a programmable memory comprising several locations for receive digital subscription blocks C _i , e) a read-only memory containing instructions allowing a recording and a selection of said subscription blocks, and a calculation, f) a calculation circuit receiving, from the receiver into which the card is inserted, digital messages M .and receiving from said first memory a digital block 'of subscription C _i , this circuit being able to run an algorithm parameterized by subscription keys C _i ,

on instruction from the second read-only memory and delivering, after calculation, a digital signal representing a service key K.

The present invention also relates to a loading station adapted to the card which has just been defined and which is characterized in that it comprises: a housing for the introduction of one of these cards,

- an interface which is coupled to the interface of the card when the latter is introduced into the station,

- a memory containing a list of work blocks for sale,

a loading circuit able to locate an empty location in the programmable memory of the inserted card, then to load said memory, at this location, by a subscription block composed of a subscription key, of an index d subscription, a service code and finally a cyclic redundancy code.

In any case, the characteristics and advantages of the invention will appear better after the description which follows, of exemplary embodiments given by way of explanation and in no way limiting. This description refers to drawings in which:

- Figure 1, already described, illustrates a videotex system provided with means of controlling access to information, Figure 2 illustrates the block diagram of circuits of the invention card,

FIG. 3 is a diagram illustrating the operation of the card,

FIG. 4 schematically represents a station for loading subscription cards.

The card shown in FIG. 2 comprises, on a support 36:

* An arithmetic and logic unit 120 managed by a control unit 122, the whole constituting a central unit capable of performing:

. arithmetic and logical operations: addition, shift, comparison, "logical AND", "OU-exclusive",. conditional logical connections,. event counts

* A program memory 124 of ROM (Read Only Memory) type containing the instructions describing the operating phases (recording, selection, calculation), the assembly 120/122/124 constituting the circuit 110; * A subscription memory 108 of type PR0M (Programmable Read Only Memory) for accommodating blocks of subscriptions,

* A working memory 128 of RAM type (Randαm Access Memory) to park the intermediate results of the calculations,

* A 130 communication interface with the outside, managing a connector with at least 6 contacts (reset, ground, inputs / outputs, power supplies, clock, extension) which allows exchanges between the card and the subscription validation machine on the one hand, and between the card and the users' receiver on the other.

All of these elements can be looked like in a monolithic integrated circuit. All of these elements form the means 36 in FIG. 1. The subscription memory 108 is organized in blocks of 21 bytes, each of which can receive a subscription block. Thus, a PROM of 4,096 binary elements is likely to contain up to 24 subscription blocks.

The locations occupied on the map are marked with occupation flags. A subscription card is full when all the flags are displayed.

The operation of this card is characterized by three phases: registration, selection and calculation.

A) The recording phase begins with the location of the first flag not displayed, that is to say of the first free location in memory 108; then, under the control of the loading station, the central unit of the card supervises the writing of the subscription block requested by the user.

A subscription block is composed for example of four fields:

1) a "service code" of 16 binary elements which designates the service considered,

2) a "subscription index" of 8 binary elements which characterizes a subscription for a service considered. Two of these binary elements indicate the type of subscription (1, 3, 6 or 12 months) and the other six indicate the month of start of subscription (1 to 60 modulo 5 years),

3) a "subscription key" of 128 binary elements which is the basic information of the block, 4) a "cyclic redundancy code" of 16 binary elements which relates to the 152 preceding binary elements and makes it possible to verify the block d subscription before using it.

A subscription block is therefore composed of 168 binary elements, or 21 bytes.

The registration phase is only one step in the overall subscription operation. Indeed, it is necessary to start by checking the correct operation of the card using a test subscription block inserted at the creation of the circuit. This test subscription block authenticates the card in passing. In addition, after the registration phase, you must check that the operation is going well. As we cannot reread what we have just written, we must therefore test again using the new registered block. B) The selection phase consists in testing the subscription blocks to locate one which corresponds to a service code indicated by the receiver from the address indicated, the response consisting in providing the subscription index and the address of the block located. The selection phase therefore begins with the provision by the receiver of a service code. The card control unit then searches the subscription memory for the first block affected by this code. When she finds one, she checks it using the cyclic redundancy code. In the absence of an incident, the card responds to the receiver by providing it with the subscription index for the block found.

Incidents can be _: "the cyclic redundancy code is bad", and "there is no suitable subscription on this card". These two incidents are signaled to the receiver by abnormal indications, for example1 ⁸ and 0 ⁸ , indications formed by 8 binary elements at 1 or at 0.

The selection phase therefore plays a dual role: actual selection and verification of the subscription block considered.

C) The calculation phase consists in calculating the service key C from the message transmitted by the receiver and the subscription key found in the memory of the card. In other words, the receiver having located the appropriate message in the access control page, it supplies this message to the card which itself has identified the suitable subscription block.

This calculation phase is repeated each time the access control page is updated, as long as the user does not disconnect from the service in question. The diagram in FIG. 3 illustrates the different states and transitions between states of the automaton constituted by the circuits of the card. The meaning of the symbols identified by references is as follows: 140 - idle state

141 - power up

142 - sleep state

143 - order to register at an address

144 - registration of a subscription block 145 - acknowledgment

146 - order to select a service from an address

147 - block selection and test

148 - supply of the subscription index and its address

149 - message calculation order using the block at the address indicated

150 - calculation of the service key

151 - supply of the service key 152 - reset to zero.

The advantage of this procedure is to avoid any vivid memorization of previous operations at the card level, and therefore to close the operating system.

The machine has no. memory, which avoids many cases of conflict and error. In addition, the card becomes deaf during the execution of an order until it gives a response.

We will now describe an example of calculation that the card of the invention can perform. However, beforehand, it is necessary to describe the algorithm which makes it possible to calculate the messages in the emission center of the videotex system from a service key and from blocks of subscriptions.

The calculation of messages from the subscription keys C _i and the key K is carried out in the broadcasting center sion by circuit 102 which is organized around a microprocessor. This circuit is programmed to implement an algorithm which is based on two Galois bodies having for characteristics the prime numbers of Mersenne 2 ⁶¹ -1 and 2 ¹²⁷ -1. This algorithm uses the subscription keys C _i (128 binary elements) and a service key K of 56 binary elements, as follows:

1º) a% confusion redundancy word is formed which includes 61 binary elements generated at random each time the algorithm is implemented;

2º) we calculate π ^{- 1} , inverse of π modulo 2 ⁶¹ -1 by an arithmetic program using a variant of Euclid's algorithm:

3º) a first multiplication is carried out by another arithmetic program: v = K.π ^-1 modulo (2 ⁶¹ -1); 4º) we calculate γ, inverse of C modula 2 ¹²⁷ -1, by a program similar to that of 2º);

5º) finally, the message is calculated by a program similar to 3º); M = γ. (v + 2 ^64. π) modulo (2 ¹²⁷ -1). The messages having been formed in this way, the algorithm to be rolled out in the card to restore the service key K from a message M _i and a subscription key C _i is as follows:

1) The message M _i (127 useful binary elements) is entered byte by byte and a multiplication by C _i is carried out on the first body CG (2 ¹²⁷ -1). We thus form a word μ: μ = M. C modulo (2 ¹²⁷ -1)

According to the construction of M on transmission, the binary elements 1 to 61 of μ represent the word v, while the binary elements 65 to 125 represent the word π. Of course, the bits 62, 63, 64, 126 and 127 must be zero. If they are not, we put the word ν to zero before continuing the calculation. 2) π and v are multiplied on the second body

CG (2 ⁶¹ -1), which eliminates the redundancy of confusion and we obtain K = v. π modulo (2 ⁶¹ -1).

A new likelihood test intervenes here since K having 56 useful binary elements, the elements 57,

58, 59, 60 and 61 must be null. In this opposite case, K set to zero before continuing operations.

3) The 56 useful bits of K are then available in the form of eight odd bytes. FIG. 4 schematically represents a loading station for the cards which have just been described. This position includes externally:

a box 160 containing a display screen 162, a housing 164 for new cards, a slot 166 for the introduction of the cards to be loaded, an outlet 168 for a printed receipt,

a keyboard 170 for controlling the operations to be carried out.

This station includes, inside the box 160: - an interface capable of being coupled to the interface of the cards inserted,

- a memory containing the list of subscription blocks for sale with the corresponding prices,

- a circuit for loading the subscription desired by the user in the card inserted. This circuit is able to locate an empty location in the programmable memory of this card and to write there the subscription block composed of a subscription key, a subscription index, a service code and finally a cyclic redundancy code. Preferably, the loading station contains a message and a test key to verify the authenticity of the cards inserted, using the test subscription they contain for this purpose. Such a loading station is linked to the subscription management center, as shown in Figure 1: it receives lists from this center. of subscription blocks for sale as well as tariffs, and it provides in return records of the transactions and the amount of taxes levied.

The transaction record then makes it possible to specify the audience for each service and to best distribute the cash flows from subscriptions. The receipt is useful in the event of a dispute on the card.

The foregoing description emphasizes the ANTIOPE system, but the invention can be applied to other systems operating on subscription (TITAN, EPEOS, etc.).

Claims

CLAIMS 1. Subscription card for videotex receivers, this card comprising: a) a support, b) information processing means including a control unit managing an arithmetic and logic unit and a random access memory, c) an interface allowing exchanges between the card and the device into which it is inserted (charging station or receiver), characterized in that it further comprises: d) a programmable memory e comprising several locations for receiving digital blocks d subscription C _i , e) a read-only memory containing instructions making it possible to carry out a recording and a selection of said subscription blocks, and to a calculation, f) a receiving calculation circuit, of the receiver into which the card is inserted , digital messages M _i and receiving from said programmable memory a digital subscription block C _i , this circuit being able to run an algorithm parameterized by keys subscription C _i on instructions from the second read only memory and delivering after calculation a digital signal representing a service key K.

2. Card according to claim 1, characterized in that the programmable memory is organized in blocks of bytes.

3. Card according to claim 1, characterized in that it comprises means for carrying out three operations of recording, selection and calculation respectively,

the recording operation consisting in recording in the programmable memory, at a location designated by an address, a subscription block comprising a service code, a subscription index, a subscription key and a cyclic redundancy code,

- the selection operation consisting in testing the registered subscription blocks in order to locate a corresponding one with a given service code, from the indicated address, the response consisting in supplying the subscription index and the address of the localized block,

the calculation operation consisting in calculating a service key from the subscription key located in the subscription memory.

4. Card according to any one of claims 1 to 3, characterized in that said programmable memory contains a space reserved for a test subscription.

5. Card loading station according to any one of claims 1 to 4, characterized in that it comprises:

a housing for the introduction of one of these cards, an interface which is coupled to the interface of the card when the latter is introduced into the station,

- a memory containing a list of subscription blocks for sale,

a loading circuit able to locate an empty location in the programmable memory of the card inserted, then to load said memory, at this location, by a subscription block composed of a subscription key, of an index d subscription, a service code and finally a cyclic redundancy code.

6. loading station according to claim 5, characterized in that the loading circuit contains a message and a test key to verify the authenticity of a card inserted, using the test subscription that it contains.